The present invention relates to skivers, and in particular to a manual belt skiver for removal of a portion of the top layer from a conveyor belt or the like.
Manual belt skivers are generally known in the prior art, and serve to remove the top layer or a portion of the top layer at the end of a conveyor belt. In this context, it is common to secure the belt against slippage in a support apparatus, and to then undertake processing with the skiver, whereby the skiver is pulled manually across the belt. In general, the construction of the belt skiver resembles that of a manual carpenter""s plane. The planar bearing surface of the belt skiver thus lies upon the conveyor belt, whereby the slanted knife that projects beyond the bearing surface cuts away strips from the top layer, such that U-shaped or wave-shaped depressions in the conveyor belt are formed. A large number of grooves can be created in the conveyor belt by repeatedly drawing the belt skiver across the entire width or breadth of the conveyor belt, thus removing the top layer or a portion of the top layer from the end of the conveyor belt. Use of the belt skiver requires a high degree of skill and physical strength, and does not ensure that the free, skived surface is absolutely even, or that the residual wall thickness of the belt is absolutely uniform at all points.
A manual belt skiver of the above-named type is disclosed in DE-PS 11 12 279. There the knife is constructed as a stable, hollow molding cutter, the cutting edge of which lies in a plane perpendicular to the plane of symmetry of the knife""s cross section, which plane, along with the outer side of the knife, encloses an acute angle, whereby two further cutting edges are provided on the exterior of the cutter head, which cutting edges deviate away from the back of the knife and which likewise lie in a plane perpendicular to the plane of symmetry of the knife""s cross section, but form a rearwardly opening acute angle with the back of the knife. A belt skiver such as this only allows grooves to be created in the top layer of the conveyor belt. The construction of the knife as a hollow molding cutter is such that only a small portion of the top layer can be removed in each cutting step during manual use of the belt skiver.
EP 0773 089 A1 discloses a manual belt skiver suitable for compressive use. In any case, its base is not moved across the conveyor belt in order to remove the top layer or the portion of the top layer from the conveyor belt, but rather along its end face. A knife in the form of a thin blade, the end of which curves upward, is held in the base and projects laterally from it. In addition, a hold down mechanism is mounted in the base which lies upon the top layer of the conveyor belt and precedes the blade during the cutting process.
An apparatus for the removal of the top layer or a portion of the top layer from a conveyor belt is disclosed in DE GM 8702 754. It is not a matter of a hand tool in this case, but rather of a mechanical apparatus with which the potential exists to introduce longitudinal grooves in a previously vulcanized conveyor belt. Here it is to be ensured that a groove of an exactly defined depth, width and contour is created in the belt""s top layer. The conveyor belt is moved relative to the stationary cutting apparatus so that a belt strip of unlimited length can be processed. These devices include a stationary holder for a blade. The blade is U-shaped in form, whereby the free ends of both of the blade""s legs are mounted in the holder.
One object of the present invention is an improved manual belt skiver of the above-named type configured so that a relatively large portion of the top layer of a belt or a portion of the top layer of a belt can be removed with minimal expenditure of energy, whereby it is ensured that the cutting forces are optimally transferred from the belt skiver into the conveyor belt via the blade.
In one embodiment of the present invention, the knife is constructed as a thin blade with a U-shaped cutting edge, whereby the blade has a central area with its cutting edge section arranged parallel to the bearing surface of the base and oriented perpendicular to the direction of motion of the belt skiver, as well as two lateral or side areas with cutting edge sections emanating from the cutting edge section of the central area and angled into the opening of the base.
One operating principle of the belt skiver according to the present invention is that its base is moved across the top layer of the conveyor belt, in combination with the specific construction of the knife as a thin blade with bilateral curved cutting edge sections at each end. Motion of the belt skiver with its bearing surface above the conveyor belt ensures that the forces introduced into the belt skiver via the handle are directly transmitted to the blade, so that no tilting moments (as noted for belt skiver contact using another functional type in which the base is guided alongside the conveyor belt) are introduced into the belt skiver. As a consequence, the belt skiver according to the present invention also needs no hold down mechanism. Based on the type of belt skiver in which the inclined knife traverses an opening in the base, and on the particular construction of the blade, it is possible to remove a top layer from the conveyor belt with each stroke of the belt skiver, the cross section of which, as limited by the bearing surface of the base, corresponds to the cross-sectional surface of the blade.
It is considered particularly advantageous if the belt skiver is moved across the conveyor belt under compression. In this regard, the central area of the blade should be arranged at an angle to the bearing surface of the base in substantial correspondence to that angle at which the compressive force for using the belt skiver is introduced into the handle. It is expedient that this angle correspond to 5 degrees to 15 degrees, preferably 7.5 degrees to 12.5 degrees, and in particular 10 degrees.
According to a particular embodiment of the invention, it is provided that the blade be constructed symmetrically. Independent thereto, the cutting edge section for each lateral area of the blade is to be arranged at an angle of 90 degrees to 120 degrees, preferably 100 degrees to 110 degrees, relative to the cutting edge section of the central area of the blade.
Particularly good cutting results can be achieved if the blade itself is constructed so as to conically widen, beginning at the cutting edge. In this context, it is expedient that the angle of the cutting flanks adjacent to the cutting edge of the blade correspond to 15 degrees to 25 degrees, preferably 17.5 degrees to 22.5 degrees, and in particular 20 degrees. In particular, the cutting flank of the blade directed away from the base is oriented parallel to the bearing surface of the base.
If the top layer of the belt or a portion of the top layer of the belt is to be removed at a distance from the end face of the conveyor belt, it is considered advantageous for the belt skiver to include a guide apparatus that serves to provide lateral contact with the end face of the conveyor belt. The guide apparatus is preferably constructed as a bar connected to the base. It should be adjustable relative to the base.
These and other advantages of the invention will be further understood and appreciated by those skilled in the art by reference to the following written specification, claims and appended drawings.